Polycarbonate is an engineering plastic widely used in the plastics industry.
Polycarbonate can have a glass transition temperature of about 150° C. by virtue of a bulky molecular structure, such as bisphenol A, and thus can exhibit high thermal resistance. Also, a carbonyl group of a carbonate group has high rotational mobility and thus can impart flexibility and stiffness to polycarbonate. In addition, polycarbonate is an amorphous polymer having superior transparency and exhibits excellent properties in terms of impact resistance and compatibility with other resins. However, polycarbonate has poor flowability and is often used in the form of alloys with various resins to complement workability and post-processability.
Among these alloys, a polycarbonate/acrylonitrile-butadiene-styrene copolymer (PC/ABS) alloy can have excellent properties in terms of durability, thermal resistance, and impact resistance and is used in various fields such as electrical/electronic products, automotive components, construction materials, and other real-world materials.
However, such a PC/ABS alloy is likely to be discolored by heat and has poor UV stability. Thus, a molded article manufactured using the PC/ABS alloy is rarely used as a component without being subjected to an appropriate post-processing process such as plating, painting, and wet transferring. For example, painting allows realization of various colors and is relatively inexpensive, as compared with other post-processing processes, and accordingly is the most common post-process.
Generally, painting sequentially includes molding a component, etching a surface of the component, application/drying of a painting solution to the component, and coating. Here, since the painting solution generally includes an organic compound solvent, defects of the component generated during a molding process such as injection molding, i.e. abnormal appearance including surface defects and surface welds or flow marks, can become more prominent after painting. In addition, residual stress on the component after molding can cause painting defects due to the organic compound solvent.
Surface cracks, erosion, and non-uniformity in appearance after painting caused by such abnormal appearance and painting defects can be partly improved through additional processes. Introduction of the additional processes, however, is not a fundamental solution since the additional processes increase complexity of the overall process and can only provide slight improvement.
Therefore, in order to overcome these problems, the present inventors have conducted a study for preparing an improved polycarbonate resin composition which can exhibit excellent paintability while maintaining superior properties of a PC/ABS alloy, such as impact resistance, by improving paintability of a material itself.